To WFN Forum Members, Is it proper to post the pedigree with the original surname when known OR keep the popular surname used in theancestor's lifetime? Wouldn't the original surname be more useful for genealogists?

Laura, the best scenario is when both of the surnames are included in the same surname project. If there are two surname projects - one serving the current surname and one serving the earlier version of the surname, then you have to pick one for testing. As you can belong to 2 surname projects, you can then join the other after your results are available.